Getting Started With a Grinding Stone – Everything You Need to Know
A grinding stone is a tool you use to sharpen your knives – and a really good investment if you want to keep your knives in top condition for life.
That said, if you're new to the world of grinding stones, it's easy to feel a little overwhelmed at first. There are different types of stones, sharpening angles, grain sizes and techniques to get your head around.
To keep things simple, I'll guide you through everything you need to know in this article.
Here's what we'll cover:
- What is a grinding stone?
- What do the different grain sizes mean – and when should you use which one?
- How do you sharpen knives with a grinding stone?
- Why the right angle matters when sharpening your knives
With that out of the way, let's dive a little deeper into what a grinding stone actually is.
What Is a Grinding Stone?
As the name suggests, a grinding stone is a stone used to sharpen knives. They come in different materials and grain sizes, each suited to a different stage of sharpening.
All grinding stones at Gastrotools are industrially manufactured – which means they have a finer and more consistent grain than stones made from natural rock. The result is a more predictable, even sharpening experience every time.
A grinding stone works a lot like sandpaper: the lower the number, the coarser the stone. A #500 grinding stone, for example, is on the coarse end of the scale. Coarse stones are used to straighten and restore the edge of the knife, while finer stones are used to polish that edge until it's beautifully sharp.
The grinding stones at Gastrotools all feature two sides with different grain sizes, so you have everything you need in one stone.
If you haven't sharpened your knives in a long time, we recommend starting with a coarse stone to fully straighten the edge first – then gradually move on to finer and finer stones for a polished, razor-sharp finish.
Are You Using the Right Angle?
When you use a grinding stone, holding your knife at the correct angle is essential. The exact angle depends on the type of knife you're working with.
As a general guide, all our knives at Gastrotools should be sharpened at around 15–20 degrees, depending on your preference. Classic Western-style kitchen knives are typically sharpened at around 20 degrees, while Japanese knives are usually sharpened at a slightly smaller angle for a finer, more precise edge.
How to Sharpen Your Knives on a Grinding Stone
We've now covered materials, angles and grain sizes – and now it's time for the most interesting part: how to actually use a grinding stone.
Step 1: Soak Your Grinding Stone in Water
Before you start sharpening, place your grinding stone in a bowl of water and let it soak for 5–10 minutes.
The reason for this is simple: when sharpening knives, we want to avoid generating any unnecessary heat – and the stone needs a little time to fully absorb the water before it's ready to work.
Why does heat matter so much? Too much heat softens the steel of the blade, which means your knife will lose its sharpness much more quickly. In the worst case, the hardening of the steel itself can be damaged. So if you ever take your knives to be sharpened by someone else, make sure they use wet sharpening too.
Step 2: Straighten the Knife Edge on the Coarse Side
Take your soaked grinding stone and place it fine side down into the included rubber base, so it stays firmly in place on your kitchen counter.
Now, hold your chef's knife at an angle of 15–20 degrees, press lightly on top of the blade and pull it down across the stone.
Repeat this 10 times, then do the same on the other side of the knife.
As you work, you'll often start to feel a small burr forming on the opposite side of the blade – a faint irregularity along the edge that you can sense by gently running your thumb across it. That's a good sign: it means the knife is being sharpened properly.
To remove the burr, finish off by gently sharpening the knife once on each side before moving on to a finer grit.
Step 3: Flip the Grinding Stone and Finish on the Fine Side
Now flip the stone over so the fine side is facing up.
Hold your chef's knife at the same 15–20 degree angle, press lightly on top of the blade, and pull it across the stone 10 times on each side.
A small note: you may notice a greyish liquid building up on the surface of the stone. That's completely normal – it's a mixture of water and fine metal residue from the blade, and it actually helps to refine the edge even further. So don't wipe it off as you go.
If you'd like your knives as sharp as razor blades, you can repeat the process on even finer grinding stones for a beautifully polished finish.
Once you're finished sharpening, simply rinse your grinding stone, let it air-dry and put it away – ready and waiting for the next time you need it.
So, Which Grinding Stone Should You Choose?
There are, of course, several options to pick from.
If I were heading off to a deserted island and could only bring one grinding stone for my knives, I'd choose our 500/1000# grinding stone. The coarse 500 side is perfect for straightening the edge, and the finer 1000 side does a brilliant job of bringing the knife to a sharp, refined finish.
That said, if I weren't heading off to a deserted island – I'd go for a set of three grinding stones, so I'd always have the sharpest knives in the drawer.
